a "mob" = "a crowd of people" "mob violence" is also often called a "riot" "mob violence" occurs when a crowd turns violent with a psychology and group dynamic that is often spontaneous, unplanned, irrational and uncontrollable. A well-disciplined police or military unit is not ordinarily engaging in "mob violence" even if they must use force to carry out their duties.

mob = lots of people Mob violence would mean that a large group of people were being violent at the same time (usually at the same place) A large group of people fighting, causing destruction to property, etc. Jerry (English tutor)